The application of decorative means to various foodstuffs, such as the surface of a cake, essentially derived over the years as an individual craft of the artisans skilled efforts in providing personalized decorations to such components. For example, early ornamentations provided to cakes, cookies and related types of foodstuffs, fairly well depend upon the skill, dexterity, and imagination of the baker, in order to get any facsimile of decoration upon the finished food product.
Various substitutes to skilled artisans have by necessity been devised for use for decorating food products, and, recently, automated systems for cake decoration have appeared on the market which allow decorating on an automatic basis. For example, U.S. Pat. No. 5,834,047 to Ahn relates to a process of imprinting diverse shapes of multiple colors inside the confectionery products with edible ink. An edible mixture of confectionery material is filled and solidified in a mold which is pressed upon by a plurality of etching plates of a predetermined shape and according to predetermined colors. The mold is rotated with a predetermined angle and number of times to disperse edible ink more than once with different colors on the surface of the solidified confectionery material. Since shapes and color combinations can be too complicated, this process may be time consuming and may be difficult to implement on the hard surface of opaque food items, such as chocolate.
U.S. Pat. No. 5,505,775 to Kitos discloses another cake decorating system, wherein a digitally stored image is transferred to the top of a cake using a print head that includes a drop-on-demand ink expulsion system which has a nozzle plate directing edible ink toward the cake's surface. This system relies on the accurate alignment and rigidity of the three-axis system to preserve image fidelity. Any departure from perpendicularity, particularly in the x and z-directions, and any play in the mutual alignment of the head supporting arm and the slide assembly supporting the cake, is reflected in a noticeable deterioration in the quality of the picture on the surface of the cake.
U.S. Pat. No. 5,795,395 to Ben-Matitayhu et al., discloses an apparatus for decorating a cake by providing a movable printing head that dispenses edible ink at positions corresponding to the pixels of a digital image. The head and the cake are displaceable relative to one another by means of a leveling mechanism, which includes adjustable legs supporting the cake supporting table. Since the head is displaceable only laterally, it is easier to keep an arm supporting the head than is the case with the above-discussed patent to Kitos. While both these methods achieve satisfactory results with products having porous surfaces, it may not be applicable to hard-surface items because the hard surface should be specifically treated so as to be able to contain edible ink.
U.S. Pat. No. 4,578,273 discloses a method of forming a food product by providing a hard, non-porous icing surface on a baked product upon which an image is imprinted. However, it may be difficult to use a jet printing method on the icing surface because edible ink may spread around this icing surface, if the latter is not properly thermally treated.
U.S. Pat. No. 4,668,521 to Newsteder discloses a typical process of forming an image on chocolate. The method includes a step of forming a photoengraving metal plate coated with an insoluble photo-etch material. The transparency bearing a halftone image of the original is placed over the plate and is exposed to ultraviolet light so as to record the halftone image on the plate's surface. After treating the plate with an acid and allowing it to dry, highlighted and shadow areas representing the halftone image is clearly discernable. The method further provides casting a screen against the plate so as to transfer the true image on a chocolate. This method requires manufacturing molds and screens and may not achieve satisfactory results of transferring the image on chocolate.
It is therefore desirable to provide an apparatus for jet printing an image directly onto a generally non-absorbent hard surface of chocolate without manufacturing additional molds and screens. Also, it is desirable to provide an apparatus of the type described above that is capable of providing high definition imaging transfer onto a non-absorbent surface of a food item. An apparatus that provides simple and reliable alignment between an item and a printing head is also desirable, as is a method for transferring an image on a hardened generally non-absorbent surface that can be automated.